Liquid fuel burning apparatus with access means



July 18, 1950 w. J. DUFF 2,515,640

LIQUID FUEL BURNING APPARATUS WITH ACCESS MEANS Filed June 20, 1947 3 Sheets-Sheet 1 Inventor WA LTE R I DU F A Horney July 18, 1950 w. J. DUFF 2,515,640

LIQUID FUEL BURNING APPARATUS WITH ACCESS MEANS Filed June 20, 1947 5 Sheets-Sheet 2 FIGS.

0 /2 I o a I g /9 I I IO Inventor WALTER J. Df/FF By 2 i .4 Horney July 18, 1950 w. J. DUFF LIQUID FUEL BURNING APPARATUS WITH ACCESS MEANS Filed June 20; 1947 3 Sheets-Sheet 3 A HIIIIIIIIh Inventor Patented July 18, 1950 LIQUID FUEL BURNING APPARATUS WITH ACCESS MEANS Walter James Duff, Ilford, England, assignor to George William Francis Richards, Chigwell,

England, and Douglas Henry King,

England London,

Application June 20, 1947, Serial No. 756,039 In Great Britain June :22, 1946 4 Claims.

This invention is for improvements .in or relating to heating apparatus such as room heaters, cookers or geysers which employ fluid fuel burners of the type in which gases and/or vapours formed by the fuel ascend in a space bounded laterally by perforated walls; through the openings of which air for combustion has access to the said space. In the normal arrangement of the above burner the perforated walls which form part of the burner head are mounted over a burner bowl which generally comprises an annular .or substantially annular grooved ring .fitted with a wick or absorbent material such as asbestos which is fed from a reservoir of liquid fuel. To light the burner, the burner head .has to be raised clear of the burner bowl.

When a burner of the above type is built into a heating apparatus such as a stove, cooker or geyser (hereinafter called stoves), it is generally located within the stove casing. Access is provided to the burner for lighting it through a door or opening provided in the stove body, and since the burner head "has to 'be lifted clear of the burner bowl for lighting, special tools have been provided .for lifting it. It will be appreciated that working through the access opening is an awkward job. One of the objects of this invention is to make the lighting of the burner an easier operation than it has hitherto been. The liquid fuel supply for such stoves is fed from a totally closed tank into a bird bathtype of sump and b gravity from the sump to the burner and another object of the invention is to improve the control of such fuel feed.

Accordingly the present invention provides a heating apparatus embodying a burner of the type described and in which the burner body is enclosed or partly enclosed in a casing of the apparatus, and in which an access door in the neighbourhood of the burner gives access to the burner body for lighting it characterised by a linkage or cam device connected to .the door and arranged to lift the burner head clear of the burner bowl when the door .is opened. Conveniently the access door is spring biased .to the closed position. Preferably the linkage is arranged to remain locked when the door is .fully opened to hold the burner head clear of the burner bowl.

In the bird bath type of liquid feed to a sump a column of liquid .is maintained in aclosed tube or tank, the lower part of which dips into the sump, and aport in the lower part-of the tank is sealed off b thelevel of 'liquidin the sump and the column of liquid is maintained by the difference in pressure acting on th free surface of the liquid in the sump and on the free surface of the liquid in the tank. When the level of the liquid in the sump uncovers the port in the tank, air bubbles flow into the tank to allow the discharge of an amount of liquid which will again raise the level of the .liquid in the sump until it seals the port in the tank and stops the feed.

None of the well known systems of fuel feed for burners provide the delicate control required by the small consumption of fuel per minute and the small difference in fuel feed between high and low burning and the second object of this invention as already referred to achieves this control with regularity even when the contents Of the fuel tank or sump expand due to heat radiated by the burner.

Examples of heating apparatus embodying the invention will now 'be described with reference to a heating stove reference being had to the accompanying drawings in which:

Figure 1 is a side elevation chiefly in section and more or less diagrammatic of the essential part of one embodiment as it appears when the stove is :alig'ht;

Figure .2 isa similar view of .a portion of Figure 1 as viewed from the opposite side of the stove;

Figure ,3 .is .a perspective .view of part of the embodiment of Figure 2 when the stove is about to be lighted;

Figures 4 and Sam views-at right angles to each other of the fuel tank of the ,stove part being brokenaway in Figure 4; and

Figure 6 is a section on the line VIVI ofFigure 5.

Referring firstto Figures 1, 2 and 3 the'stove body is :in the form of a sheetrmetal casing I, the lower part of'which is more or less triangular (in plan view) with three :feet 2 so that the stove will accommodate itself to uneven surfaces. The lower triangular part is swept upwards and backwards to form-an upper part and rear chamber 3 which will house a fuel tank 4. A louvred top plate 5 is pivoted to the rear wall of the casing and provides access to the fuel tank. The front wall of the upper part .of the casing carries a bright bowl reflector it, and several (preferably three) baflle plates 'I are located .inside the upper partof the casing to screen the tank .from the heat. The lower front part of the casing forms a compartment to :house the burner unit which includes /a bowl t8, 'preferablyrof the Wick containing type, that amovably supports ;a burner head 8 with the upper part 9 of the burner head (which may have a glowing grid or other radiant means) located in front of the bowl reflector 6.

Opposite the burner, the casing has an access door I which is preferably pivoted along its lower edge as by a hinge II so that it opens outwards and downwards as shown in Figure 3. Secured to the inside of the door III are a pair of bent levers I2 which flank the burner and have a pin and slot connection I3 with a pair of links I4 pivoted at the rear of the front compartment, the arrangement being such that the links I4 are raised as shown in dot-dash lines in Figure 2 when the access door I!) is opened. Two flanged lifting brackets I5 are carried by the links I4 and lie under the ends of lifting rods I6 secured to the burner head 8. These rods I6 in Figures 2 and 3 pass through guide blocks I! which are fixed on the burnerbowl I8. A spring in the form of a tension hinge I9 co-operates with the pivot of the lifting links I4 so that the spring is tensioned when the door IUisopened to bias the door in the closing direction. The normal position of the flanges on the lifting brackets I5 when the door is closed, is such that these brackets are spaced from the ends of the lifting rods It to allow for expansion of the latter when the burner is lit without the rods tending to lift the burner head clear of the burner bowl I8. The hinge spring I9 ensures that the lifting links I4 and brackets I5will take up this position clear of the ends of the rods, and at the same time ensures that the access door will close firmly to exclude draughts which might upset the burning of the burner. If desired, the links I4 may b so arranged that when the door is fully open they are in a position of equilibrium to hold the burner head clear of the burner bowl I8 for lighting but when the door is partially closed away from this position, the weight of the burner head assists the closing movement.

In Figure l the links I4 instead of being provided with lifting brackets I5 as illustrated in Figures 2 and 3 embody a'modification in which two arms secured to the burner head and with bifurcated ends 2| lie over and straddle the links so as to permit a limited lost motion of the links relatively to the bifurcated ends when the links are raised by the door. In this arrangement the burner head is guided in its movement to and from the burner bowl I8 by guide sleeve 22 fixed axially inside the burner head and sliding on a fixed pillar 23 supported from the casing.

A horizontal baflie 24 extends across the casing below the burner to prevent heat radiated by the burner from damaging the surface on which the burner sits.

The fuel feed system of the stove is characterised by a valve device co-operating with a port or ports in the tank, the said port or ports extending in the direction of the depth of a sump, whereby the level of liquid in the sump may be varied by adjustment of the valve device as will appear from the description now about to be given more particulary of Figures 4, 5 and 6.

The fuel tank 4 is located as shown in Figure 1 inside the stove casing, base 24 upwards and a lifting handle 25 is provided on the base for lifting the tank out of the casing. The lower end of the tank has a cylindrical neck 26 closed by a filling plug 21 and provided with a slotted port 28 which forms the outlet from the tank. A level control pipe 29 is secured to the outside wall of the tank and has a slotted port 30 in register with the port in the tank and another similar slotted outlet port 3 I. A rod or tube 32 with an operating knob 33 at its upper end slides in the level control pipe 4 29 so that adjustment of the rod along the pipe closes or opens the ports therein. Thus the end of the rod working in the lower end of the control pipe forms at such lower end a valve chamber of variable depth according to the position of the rod relatively to the slotted ports.

The neck 26 of the tank and the end of the level control pipe 29 are located within a liquid fuel sump 34 Figure 1 so that liquid flowing from the tank through the ports in the control pipe will fill the sump up to the level of the slotted ports exposed by the valve rod 32. The fuel is fed from the sump 34 to a fuel feed pipe 35 connecting the sump to the burner bowl I8. The inlet end of the fuel feed pipe is located at a lower level than the burner-bowl and the pipe extends across the base of the burner-bowl and is anchored to the front end of the lower compartment of the casing. Communication is established between the burner-bowl I8 and the feed pipe by way of small ports 36 in the base of the bowl registering with small ports in the feed pipe. The fuel from the sump 34 flows into the feed pipe 35 over a weir 37 or wall located close to the inlet end of the pipe so that when the burner is extinguished (by shutting the control valve described) there is a small and controlled amount of fuel available for the feed pipe to ensure that the burner will be extinguished quickly and in a smell-free manner. A too-quick cut-off for fuel results in the burner smoking before it goes out. A meshed screen 38 is located in the sump to trap any moisture which may have settled in the sump and prevent it reaching the feed pipe.

The position of the valve rod 32 in the level control pipe 29 is controlled by a pin 39 on the rod engaging in a gate 40 on the pipe so that the depth of the valve chamber and hence of the liquid in the sump can be adjusted between say high and low burning. One position in the gate corresponds to off in which position the ports in the level control pipe are closed.

It is important that the width of the ports in the valve chamber should not be such that a meniscus cannot form on the ports to seal them. In general it will be found that satisfactory control cannot be obtained when the port Width exceeds and it is preferred that less than /8" wide ports or slots should be employed.

The action of the system is as follows: When the tank 4 is filled with oil and placed on the sump 34 with the valve in the fully down, or closed, position, the valve rod 32 has completely closed the slots 28, 30, 3| in the level control pipe and tank, thus preventing any oil leaving the tank, the final seal being made by the skin tension of the oil; if the valve rod 32 is pulled up until, say, half of the length of the slots is free, oil will flow from the tank and fill the sump and burner-bowl I8 until the free surface of the oil in the sump 34 is level with the bottom of the rod, the skin tension of the oil will then make a seal, and prevent further air from entering the tank, and the partial vacuum thus formed inside the tank will hold the oil in the tank until oil is consumed from the sump, thus lowering the level of the free surface and breaking the seal at the valve. This allows air to enter the tank, and break the vacuum and permits oil to flow from the tank into the sump, raising the level of the free surface of the oil in the sump until it remakes a seal at the valve. It can thus been seen that any desired level Within the range of the length of the slot can be obtained in the sump by moving'the valve rod 32 up or down.

From the foregoing description it will be seen there is provided a fuel feed system of the type described, in which a valve chamber is located with its axis extending in the direction of the depth of the sump, and has ports providing an inlet from the tank to the chamber and an outlet from the chamber to the sump, and in which a valve is adjustable in the chamber for varying the depth thereof and thereby the area or number of the inlet and outlet ports exposed to the sump. This valve chamber is employed so that the free surface of the liquid in the valve chamber will form a meniscus to seal oif the ports at any position of adjustment of the valve along the chamber. section, is wedged shape at the walls of the valve chamber; thus when the level of liquid in the valve chamber (which is the same as, the level of liquid in the sump) sinks, due to the consumption of fuel, a thinner part of the meniscus is brought opposite the ports sealed by the liquid in the valve chamber, and a condition results in which the atmospheric air pressure breaks down the skin tension of the liquid adjacent to the ports and a small air bubble is able to flow into the fuel tank and permit a corresponding small quantity of liquid to flow into the valve chamber and sump, thereby raising the level of the liquid in the valve chamber and again sealing off the ports. It might be said that when the outside air pressure exerts a force on the meniscus of the liquid which is above the elastic limit of that meniscus, the latter breaks down and momentarily permits a flow of air through the ports.

Furthermore there is provided a fuel feed system of the type described and comprising a level control pipe disposed substantially vertically in the sump, and having one or more inlet ports open to the tank and one or more outlet ports open to the sump and a valve adjustable along the pipe to control the number or area of the inlet and outlet ports exposed, characterised by the fact that the area of the ports in the level control pipe is insufiicient to stretch the meniscus of the liquid in the control pipe beyond its elastic limit, so that the said ports are sealed by the liquid in the control pipe, except when atmospheric pressure is capable of breaking down the said meniscus and producing a small air flow through the said ports.

I claim:

1. A heater comprising a casing, a burner unit in said casing and including a fuel receiving bowl which opens upwardly and is rigidly supported in said casing and a burner head removably seated on said bowl for normally covering said bowl This meniscus, in vertical crossopening but being removable for access to the bowl opening, a door in said casing for access to said burner unit, and linkage connecting said door with said burner head and operative upon the opening of said door to lift said burner head from said bowl to permit access to said bowl opening.

2. A heater as defined in claim 1 wherein said linkage comprises a lost motion connection to insure complete seating of said head on said bowl during operation of said burner unit.

3. A heater comprising a casing, a burner unit in said casing and including a fuel receiving bowl which opens upwardly and is rigidly supported in said casing and a burner head removably seated on said bowl for normally covering said bowl opening but being removable for access to the bowl opening, a door in said casing for access to said burner unit and being hinged at its bottom to said casing by a horizontally disposed hinge, a pair of arms on the inner side of said door, a pair of generally horizontal links hinged in said casing on each side of said burner unit and rearwardly of said burner unit, pivotal connections between said links and said arms respectively whereby said links are raised by said arms upon opening of said door, and support members rigidly fixed to said burner head and respectively overlying said links for engagement with said links when the links are lifted to lift said burner head from said bowl.

4. A heater as defined in claim 3 wherein said support members are substantially free of said links when the latter are in their lowermost position to permit the complete seating of said burner head on said bowl, and springs interposed between said casing and said links for biasing said links to their lowermost positions to insure freedom from said support members and to bias the door to closed position.

WALTER JAMES DUFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 189,655 Rigby Apr. 17, 1877 625,124 Ruppel May 16, 1899 1,116,790 Bothwell Nov. 10, 1914 1,128,937 Boekenkamp Feb. 16, 1915 1,370,891 Huenefeld Mar. 8, 1921 1,454,265 Brennan May 8, 1923 1,582,001 Giammatteo Apr. 20, 1926 1,597,651 Hoffman Aug. 24, 1926 

